Gas operated bolt mechanism



y 4, 1967 D. E. SEGREST GAS OPERATED BOLT MECHANISM 3 She ets-Sheet 1 INVENTIOK. Ma.

Day/e E. Segresf Filed Sept. 15, 1965 WWW Fm July 4, 1967 D. E. SEGREST 3,329,064

GAS OPERATED BOLT MECHANISM Filed Sept. 15, 1965 3 $heets-Sheet 2 w w m Q m \N\ a? N M? g: W m 9 cf Q N s 1 E \Q\ H N E: mm aw g w v a E m mm m T wv M M y a M 0 m mm mv NQ No ...i r vv mm B km mm vm mm mm mm mm 3 mm M 9k \QQ Q mm QT V u g an N l \m wm m wk ww m Q I 5. wk il m I QM W y 1967 D. E. SEGREST GAS OPERATED BOLT MECHANISM 3 Sheets-Sheet,

Filed Sept. 15, 1965 mm mm WK m mm 1 JWD Doyle E. Segresf l N VE N TOR BY WM 15. Mike United States Patent 3,329,064 GAS OPERATED BOLT NECHANISM Doyle E. Segrest, P.O. Box 431, Woodville, Tex. 75979 Filed Sept. 15, 1965, Ser. No. 487,372 9 Claims. (Cl. 89-191) ABSTRACT OF THE DISCLOSURE A removable attachment for the barrel of a firearm whereby automatic, gas operated bolt action is obtained. Gas under pressure behind the projectile charges an adjustable volume chamber through an orifice to controllably pressurize a piston chamber having a stroke limiting vent port. Movement of the piston through its stroke initially unlocks the bolt from a forward firing position and subsequently moves the bolt rearwardly to open the shell ejection port in the receiver chamber of the barrel.

This invention relates to improved operating mechanisms for weapons and more particularly to automatic gas operated bolt mechanisms for firearms.

Gas operated shotgun and rifle bolt mechanisms have obtained widespread use in the industry as this means for automatic operation provides an etlicient manner of utilizing the exhaust gases produced by the firing of a weapon. The prior arrangements insofar as known to the inventor, provide internally mounted built-in gas operated mechanisms which require highly machined parts and thereby make the weapon rather expensive to produce. A need has developed for a cheaper yet still effective arrangement for utilizing the exhaust gases of a weapon for automatic bolt operation, which may be built onto new weapons or readily added to existing single shot weapons. This need has not been satisfied by existing prior art devices. Accordingly, it is an object of the present invention to provide an efiicient arrangement for utilizing the exhaust gases produced by weapons which may be built into newly produced weapons or readily added to existing weapons thereby providing for automatic bolt operation.

It is another object of the instant invention to provide apparatus which may be readily added to existing single shot weapons for converting them to repeating or semiautomatic weapons.

It is a still further object of the present invention to provide an externally mounted gas operated bolt mechanism for use with weapons.

It is a final object of the present invention to provide a mechanism for use with single-shot shotguns which utilizes the exhaust gases produced by the firing thereof to operate a readily removable, externally mounted action rod and bolt carrier to efiectively convert to semiautomatic operation.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a partial top plan view of the barrel and receiver of a shotgun having the apparatus of the present invention mounted thereon;

FIGURE 2 is a side elevational view corresponding to FIGURE 1 of the weapon with the apparatus comprising the present invention mounted thereon;

FIGURE 3 is a longitudinal sectional view taken through the barrel and receiver sections as illustrated in FIGURES 1 and 2;

of the present invention in a retracted or unlocked position;

FIGURE 5 is a longitudinal sectional view taken through the barrel and receiver sections of the weapon illustrated in FIGURE 4;

FIGURE 6 is a vertical sectional view taken substantially on the plane of the line 6-6 of FIGURE 3;

FIGURE 7 is a vertical sectional view taken substantially on the plane of the line 7-7 of FIGURE 3;

FIGURE 8 is a side elevational view of a weapon utilizing the mechanism of the present invention thereon;

FIGURE 9 is a perspective view illustrating the piston, action rod and bolt carrier comprising a portion of the present invention;

FIGURE 10 is an enlarged partial longitudinal crosssectional view illustrating certain internal mechanism of a weapon having the mechanism of the present invention in place thereon; and

FIGURE 11 is a partial enlarged sectional view illustrating the locking lug which comprises a portion of the present invention.

Referring now to the drawings in more detail, reference numeral 10 generally denotes a shotgun, which conventionally is a single shot shotgun, converted to semiautomatic operation by the gas operated bolt mechanism generally denoted by reference numeral 12. The shotgun 10 includes a barrel 14, receiver unit 16 and stock 18. The barrel 14 is a conventional elongated tubular member and the receiver unit 16 includes a tubular receiver chamber 20 therein. The receiver unit 16 is conventionally attached to the barrel 14 as for example by the encircling flange 24 thereon more clearly seen in FIGURE 10. Mounted in the receiver unit is a conventional trigger mechanism 26 including trigger member 28, finger guard 30, striker 32 and firing pin striker rod 34. A bolt 36 is retained in the receiver chamber 20 of receiver unit 16 for reciprocating or sliding movement therein. The bolt 36 is of generally conventional variety and forms no part of the present invention. The bolt 36 includes a firing pin 38 therein which extends therethrough and is held therein by the removable plug 40. The firing pin striker rod 34 is normally in engagement with the firing pin 38, and, in conventional manner, the trigger mechanism causes the striker 32 to strike the striker rod 34 which in turn causes the firing pin 38 to contact a shell 42 in the firing position in the barrel 14 as shown in FIGURE 3 and 10.

When a shell 42 is fired, the powder charge therein causes gases to expand rapidly down the barrel as the projectile or shot is released from the shell, the gases normally escaping from the forward end of the barrel. However, it is the purpose of the present invention to utilize the gas pressure in the barrel behind the projectile prior to the release of the gases from the barrel end. Toward this end, a gas orifice outlet 44 is first drilled in the underside of the barrel 14 as shown in FIGURES 3 and 5, and a generally cylindrical gas receiving chamber 46 is attached to the barrel 14 in fluid sealed engagement with the orifice 44 as for example by weld 48 thereon. A closing plug 50 is threadedly mounted in the open end of the chamber 46 to facilitate cleaning of orifice 44 and to adjust the volume of the receiving chamber. Thus, it will be apparent that when the shell is firedthereby releasing gases down the barrel, when the projectile is justpast the orifice 44, the gases behind the projectile will be rapidly expanding. The pressure of these gases will force a substantial portion thereof through the orifice 44 and into the chamber 46. A gas cylinder 52 is mounted under the barrel 14 having its longitudinal axis substantially parallel to the longitudinal axis of the barrel, the gas cylinder 52 being rigidly fixed to the barrel as, for example, by being welded thereto, as well as being fixed to the gas receiving chamber 46. The gas cylinder 52 is open at both ends but closed at the end mounted against chamber 46 by the outer wall of the chamber 46.

In the outer wall of chamber 46 which forms a closure for one end of cylinder 52 is a gas outlet orifice 54, which outlet orifice allows the gas received in chamber 46 to escape into gas cylinder 52. A piston 56 of generally cylindrical configuration having an open end 58 and a closed end 60 is slidably received in the gas cylinder 52. The open end 58 of piston 56 is opened to receive the gas escaping from outlet orifice 54 into gas cylinder 52. A chamber 62 is formed in the piston 56 and will receive the expanding gas escaping from outlet orifice 54, the pressure of the gas expanding against the end wall 60 of piston 56 thereby forcing the piston out of the gas cylinder 52.

Piston 56 has threadedly received in the end wall thereof at 64 an action rod 66 which is an elongate generally circular rod the longitudinal axis of which is parallel to the longitudinal axis of barrel 14. A supporting member 68 is attached to the barrel 14 at 70, the supporting member receiving the action rod 66 therein for sliding support thereof and further comprising a seat for one end of the compression coil spring 72 which is wrapped about the action rod 66 and seated also against the end wall of piston 56. Thus, it will be apparent that when gas enters gas cylinder 52 under pressure, the piston 56 will be forced outwardly of the end of the cylinder 52 thereby carrying the action rod 66 therewith. Of course, the pressure of the gas acting against the end wall 60 of piston 56 must overcome the compressive strength of spring 72 in order to force the piston 56 out of the cylinder 52.

Piston 56 is in substantially gas sealed relationship with the inner walls of gas cylinder 52 so that the gas entering cylinder 52 will not escape between the walls of piston 56 and cylinder 52. Further, the piston 56 is provided with a flexible end portion 74 substantially thinner than the rest of the piston wall, being thinnest at the forward end of the piston and tapering rearwardly from the front edge. When gas is forced into cylinder 52 and impinges on the inner wall of piston 56, the gas will cause the inner end portion 74 of piston 56 to flex outwardly thereby increasing the sealing engagement of the piston walls with the inner cylinder walls and creating somewhat of a drag or brake on the piston.

Action rod 66 includes an arcuate portion 76 at substantially right angles to the portion 67 attached to piston 56, the arcuate portion 76 being shaped to conform to the cylindrical wall of barrel 14 and extending approximately 90 upwardly adjacent the side of barrel 14 as illustrated in FIGURES 2 and 4. Attached to the upper end of arcuate portion 76 is a rearwardly extending portion 78 of action rod 66 which is generally rectangular in cross section and extends substantially parallel to the front portion 67 of action rod 66. A bolt carrier 80 is integrally attached to the rear portion of the rearwardly extending portion 78 of action rod 66 and is arcuate in shape to closely conform to the arcuate construction of the upper wall 82 of receiver unit 16. Thus, it will be apparent that when the piston 56 is caused to move outwardly of gas cylinder 52, the action rod 66 will cause the bolt carrier 80 to slide rearwardly over the receiver unit 16.

The bolt carrier 80 includes a helical cam slot 84 extending through the upper wall thereof receiving the projecting follower lugs 86 carried by the bolt 36. Thus, by viewing FIGURES 5 and 10, for example, it will be observed that rearward movement of bolt carrier 80 in response to movement of action rods 66 and 78 will carry the bolt 36 rearwardly in the receiver unit and will further cause the bolt to rotate in a manner well known to those skilled in the art thereby carrying the previously fired spent shell 42 into alignment with ejection port 88, and causing the spent shell to be ejected laterally outwardly of the receiver unit through port 88. Thus, the bolt 36 is caused to move in the chamber 20 formed in receiver unit 16, the chamber 20 being closed at the rearward end thereof by receiver plug 87.

Referring to FIGURE 1, the bolt 36 is shown in its forward position with bolt carrier also being in the forward position, the piston 56 being fully received in cylinder 52. The upper wall 82 of receiver unit 16 includes an elongated guide slot therein which opens as its forward end adjacent to the ejection port 88. Further, there is a shoulder 92 more clearly seen in FIGURE 5 against which the projecting lug 86 normally is seated when the bolt 36 is in its forward or closed position. The shoulde-r 92 provides a locking position for the bolt 36 inasmuch as the lug 86 is positioned thereagainst and thus the bolt cannot move rearwardly in chamber 20. The weapon may then be fired by activation of firing pin 38 and the bolt 36 will provide a closed rear end for barrel 14. However, when bolt carrier 80 begins its rearward movement, the bolt 36 is rotated thereby causing lug 86 to rotate into alignment with slot 90 and carrying the lug 86 rearwardly in slot 90, this constituting the unlocked position of the bolt 36. Further, as the bolt 36 moves rearwardly in chamber 20, the trigger mechanism 26 will be cocked in a conventional manner. Bolt carrier 80 includes a pair of inturned pivot lugs 81 and 83 thereon as shown in FIGURE 7, which lugs ride in slots 85 and 89 in order to retain carrier 80 in sliding engagement on wall 82.

An operating handle 94 is attached to the bolt carrier 80, as shown in FIGURE 1, thereby providing for manual operation of the bolt carrier and bolt if so desired whereby the bolt 36 may be selectively moved to positions respectively shown in FIGURES 3 and 5. A locking lug 96 is also provided on bolt carrier 80, the locking lug 96 being slidably mounted in the carrier 80 for vertical movement therein. The locking lug 96 is normally biased to its upward position by coil spring 98, at which time the carrier 80 is freely slidable over wall 82 of receiver unit 16. However, the wall 82 includes a cross-cut 100 near the rear end thereof into which the locking lug 96 may be depressed as shown in FIGURE 11, at which time it will be locked therein by the forward force exerted on carrier 80 by spring 72. This enables the bolt carrier 80 to be locked in the rearward position shown in FIGURES 4 and 5 thereby retaining the bolt 36 in its rearward position leaving the internal area of receiver unit 16 adjacent the ejection port 88 open for free access to the interior thereof. When it is desired to move the carrier forward, the locking lug 96 may be moved out of the crosscut 100 by pulling the carrier rearwardly by operating handle 94 at which time the locking lug 96 will be forced upwardly out of the cross-cut 1-00 by spring 98 and the carrier 80 is then moved forwardly by spring 72.

The gas cylinder 52 also includes a gas discharge orifice 102 in the bottom wall thereof approximately halfway between the ends of the cylinder 52. Thus, it will be apparent that the gas entering cylinder 52 through orifice 54 will initially force the piston 56 rearwardly out of the cylinder 52 until the piston passes orifice 102, at which time the gas is discharged through orifice 102 to the atmosphere. When the gas in cylinder 52 has escaped through orifice 102, the force of spring 72 will force the piston 56 back into the cylinder 52 thus carrying the bolt carrier 82 forwardly in an automatic step for reloading the weapon.

A magazine 104 is positioned in the bottom of receiver unit 16 adjacent the trigger 26 having the upper end thereof open to chamber 20. The magazine 104 is held in the receiver unit 16 by magazine locking member 106 which is attached to barrel 14 and which engages a flange portion 108 on the body of magazine 104 being held in engagement therewith by spring 110. By viewing FIGURE 10,

it will be appreciated that the magazine locking member 106 may be withdrawn against the force of spring 110 thus releasing magazine 104 and allowing it to be withdrawn from the receiver unit 16. The magazine 104 conventionally holds three shells 42 therein, the shells 42 being normally biased upwardly by the force of spring 112 positioned in the bottom of magazine 104. Thus, it will be appreciated that the magazine 104 is loaded by forcing the shells 42 downwardly therein against the force of spring 112 at which time the magazine is mounted in place in receiver unit 16 by being forced upwardly therein. The front surface 114 of magazine locking member 106 is slanted so that pressure from the upper portion of flange 108 thereagainst will force the locking member 106 outwardly thus allowing the magazine to be locked in place in receiver unit 16 merely by pushing it upwardly therein.

When the carrier 80 forces the bolt 36 rearwardly in chamber 20 of receiver unit 16 and the spent shell 42 has been ejected outwardly of the receiver unit 16 through ejection port 88, a fresh shell will be moved upwardly into place by the force of spring 112. When the piston 56 is forced back into the cylinder 52 by the force of spring 72, the bolt 36 during its subsequent forward movement in chamber 20 will carry the fresh shell into firing position in the barrel 14 as illustrated in FIGURE 10. As mentioned above, at this time the trigger mechanism 26 is also cocked and thus if the trigger 28 is pulled the firing pin 38 will cause the fresh shell to be fired as the firing pin 38 moves thereagainst. Of course, a spring 39 is provided in the bolt 36 to return the firing pin 38 to neutral position after the weapon is fired. At this time, the cycle is repeated as exhaust gases again force the piston 56 out of cylinder 52.

Referring now to FIGURES 2 and 11, it will be observed that the forward end of bolt carrier 80 includes a tapered wall portion 116. This tapered end of the carrier 80 provides room for the carrier to be pivoted on the upper wall 82 of receiver unit 16 about the pivot lugs 81 and 83 as shown by dotted line in FIGURE 2 when the piston 56 is pulled out of cylinder 52 and thus allows the action rod assembly and carrier to be removed from the shotgun. Of course, a slot 118 (FIGURE 8) also is provided in the supporting member 68 in order to remove the action rod 66 therefrom. Further, the plug 87 normally must be removed in order to slide the carrier off of receiver unit 16.

A one piece stock 120' of generally conventional variety is provided to cover the operating mechanism of the present invention, the stock normally being fabricated from wood or plastic material and including the proper openings therein for accommodating the mechanism.

The operation of the above device may be summarized as follows: the gas created when the weapon is fired is forced through orifices 44 and 54 into cylinder 52 thus forcing piston 56 outwardly of the cylinder 52. The action rod 66 is thus moved with the piston 56 against the force of spring 72 and the helical slot in bolt carrier 80 which is in engagement with lug 86 causes the bolt 36 to unlock by rotation thereof and thence move rearwardly in the receiver unit 16. At this time the spent shell is ejected through ejection port 88 and a fresh shell is injected into the chamber 20 from magazine 104. As the piston 56 moves outwardly of cylinder 52 against the force of spring 72 the gas will escape through orifice 102 and the spring 72 will then force the piston back into cylinder 52. At this time, the carrier 80 will carry the bolt 36 forwardly in chamber 20, thus forcing a fresh shell into firing position in barrel 14 and cocking the trigger mechanism, while at the same time rotating bolt 36 and locking it in place. This constitutes one complete cycle of operation of the gas operated bolt mechanism.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. In a gas operated system adapted to be added to an existing firearm having a receiver unit and a barrel, the improvement comprising, a gas outlet orifice in said bar rel, means mounted exteriorly of said barrel for receiving the gas through said outlet orifice, means defining a cylinder mounted exteriorly of said barrel for receiving the gas from said receiving means, piston means slidably carried in said cylinder, means for causing said piston means to be moved selectively out of and into said cylinder, a bolt slidably carried in said receiver unit, bolt carrier means drivingly connected to said bolt, means operatively connecting said piston means to said bolt carrier means whereby movement of said piston means will cause said bolt carrier means to move thereby automatically operating said bolt, connecting means between said bolt and bolt car-rier means comprising a lug on said bolt, and a helical slot in the bolt carrier means receiving said lug whereby longitudinal sliding movement of said bolt carrier means along said receiver unit will cause said bolt to move longitudinally and rotatably in said receiver unit, said bolt carrier means being in sliding contacting engagement with the upper wall of said receiver unit, said bolt carrier means including a tapered wall portion out of engagement with said receiver unit whereby said bolt carrier may be readily removed from said receiver unit.

2. A gas operated automatic bolt mechanism for use with a firearm including a receiver unit having an upper Wall, a barrel and a bolt slidably carried in said receiver unit, said mechanism comprising, a gas outlet orifice in said barrel, chamber means adapted to be mounted on the barrel in gas receiving relationship with said orifice, piston means carried in said chamber means and longitudinally slidable therein in a path substantially parallel to the longitudinal axis of the barrel, an elongate arm connected at one end to said piston means and extending longitudinally outwardly of said chamber means along the barrel, a bolt carrier connected to the other end of said elongate arm slidably and pivotally mounted on the upper Wall of said receiver unit, said bolt carrier being in operative engagement with said bolt whereby upon longitudinal movement of said piston means said bolt carrier will cause said bolt to slide in said receiver unit.

3. The combination of claim 2 including means in engagement with said piston means for biasing said piston means in a direction opposite to that caused by the gas introduced into said chamber means.

4. In combination with a firearm having a barrel and a receiver chamber portion within which a bolt is slidably displaceable between a forward firing position and a rear ejection position, an automatic bolt operating mechanism comprising, pressure operated piston means slidably and pivotally mounted on said barrel for movement parallel thereto, fluid pressure storing chamber means mounted on the barrel in restrictive fluid communication with the piston means enclosing an outlet orifice formed in the barrel and drive means drivingly connecting the piston means to the bolt for sequentially imparting angular and longitudinal movement to the bolt.

5. The combination of claim 4 wherein said piston means comprises, a bolt carrier slidably and pivotally mounted on the receiver chamber portion of the barrel, a hollow piston element, an action rod connecting said piston element to the bolt carrier, a tubular chamber member having one end closed by said pressure storing chamber means and an opened end slidably receiving the piston element, and a support element fixed to the barrel and slidably supporting the action rod having a slot through which the rod is pivotally displaceable with the bolt carrier after the piston element is withdrawn from the tubular chamber member.

'6. The combination of claim 5 wherein said piston element includes a flexible end portion expansible under pressure into sealing engagement with said tubular chamber member.

7. The combination of claim 6 wherein said drive means comprises cam means formed in the bolt carrier, a follower element connected to the bolt and received in said cam means, a longitudinal guide slot formed in the receiver chamber portion receiving the follower element, and locking means including an abutment edge on the receiver chamber portion engaging the follower element when misaligned with the guide slot in the forward firing position of the bolt.

8. The combination of claim 4 wherein said drive means comprises cam means connected to the piston means, a follower element connected to the bolt and received in said cam means, a longitudinal guide slot formed in the receiver chamber portion receiving the follower element, and locking means including an abutment edge on the receiver chamber portion engaging the follower element when misaligned with the guide slot in the forward firing position of the bolt.

9. The combination of claim 4 wherein said pressure storing chamber means includes a tubular member extending transversely from the barrel having an opened end, a removal plug closing said opened end and a restrictive passage formed in the tubular member between the barrel and the plug in fluid communication with the piston means.

References Cited UNITED STATES PATENTS 1,025,132 5/1912 Douglas.

1,338,649 4/1920 Gabbett-Fairfax 89-193 1,344,991 6/1920 Cunningham 89-191 X 1,388,879 8/1921 Nelson 89-193 1,835,286 12/1931 Dickinson 89-191 X 2,386,205 10/1945 Garand 89-191 X 2,539,644 1/1951 Turner 89-191 X 2,582,989 l/l952 Harvey 89-193 2,941,450 6/1960 Crittendon et a1. 89-191 BENJAMIN A. BORCHELT, Primary Examiner.

S. C. BENTLEY, Assistant Examiner. 

1. IN A GAS OPERATED SYSTEM ADAPTED TO BE ADDED TO AN EXISTING FIREARM HAVING A RECEIVER UNIT AND A BARREL, THE IMPROVEMENT COMPRISING, A GAS OUTLET ORIFICE IN SAID BARREL, MEANS MOUNTED EXTERIORLY OF SAID BARREL FOR RECEIVING THE GAS THROUGH SAID OUTLET ORIFICE, MEANS DEFINING A CYLINDER MOUNTED EXTERIORLY OF SAID BARREL FOR RECEIVING THE GAS FROM SAID RECEIVING MEANS, PISTON MEANS SLIDABLY CARRIED IN SAID CYLINDER, MEANS FOR CAUSING SAID PISTON MEANS TO BE MOVED SELECTIVELY OUT OF AND INTO SAID CYLINDER, A BOLT SLIDABLY CARRIED IN SAID RECEIVER UNIT, BOLT CARRIER MEANS DRIVINGLY CONNECTED TO SAID BOLT, MEANS OPERATIVELY CONNECTING SAID PISTON MEANS TO SAID BOLT CARRIER MEANS WHEREBY MOVEMENT OF SAID PISTON MEANS WILL CAUSE SAID BOLT CARRIER MEANS TO MOVE THEREBY AUTO- 